Summary of Classic and practical SQL Server statements (i)

Brief introduction to the underlying statement:
1. Description: Create DATABASE
CREATE DATABASE Database-name
2. Description: Delete Database
Drop Database dbname
3. Description: Back up SQL Server
---to create a device that backs up data
Use master
EXEC sp_addumpdevice ' disk ', ' testback ', ' C:\mssql7backup\MyNwind_1.dat '
---start Backup
BACKUP DATABASE pubs to Testback
4. Description: Create a new table
CREATE TABLE TabName (col1 type1 [NOT NULL] [primary key],col2 type2 [NOT NULL],..)
To create a new table from an existing table:
A:create table tab_new like Tab_old (create new table with old table)
B:create table tab_new as Select Col1,col2 ... from tab_old definition only
5. Description:
Delete new table: Drop table TabName
6. Description:
Add a column: Alter table tabname add column col type
Note: Columns cannot be deleted after they are added. DB2 the column plus the data type can not be changed, the only change is to increase the length of the varchar type.
7. Description:
To add a primary key:Alter table TabName Add primary key (COL)
Description
To delete a primary key:Alter table TabName Drop primary key (COL)
8. Description:
Create an index: Create [unique] index idxname on tabname (col ...)
To delete an index:Drop INDEX Idxname
Note: The index is immutable and you must remove the rebuild if you want to change it.
9. Description:
Create a View: Create VIEW viewname AS SELECT statement
Delete a view: Drop View ViewName
10, Description: A few simple basic SQL statements
Select: SELECT * FROM table1 where range
Insert: INSERT INTO table1 (field1,field2) VALUES (value1,value2)
Delete: Delete from table1 where range
Update: Update table1 set field1=value1 where range
Find: SELECT * FROM table1 where field1 like '%value1% '---the syntax of like is very subtle, check the information!
Sort: SELECT * FROM table1 ORDER by FIELD1,FIELD2 [DESC]
Total: SELECT Count * as TotalCount from table1
sum: select SUM (field1) as Sumvalue from table1
Average: Select AVG (field1) as Avgvalue from table1
Maximum: select Max (field1) as MaxValue from table1
Minimum: select min (field1) as MinValue from table1
11. Description: Several advanced query operation words
a:union operator
The UNION operator derives a result table by combining the other two result tables (for example, TABLE1 and TABLE2) and eliminating any duplicate rows in the table. When all is used with the Union (that is, union ALL), duplicate rows are not eliminated. In both cases, each row of the derived table is either from TABLE1 or from TABLE2.
b:except operator
The EXCEPT operator derives a result table by including all rows in TABLE1 but not in TABLE2 and eliminating all duplicate rows. When all is used with EXCEPT (EXCEPT all), duplicate rows are not eliminated.
C:intersect operator
The INTERSECT operator derives a result table by including only rows in TABLE1 and TABLE2 and eliminating all duplicate rows. When all is used with INTERSECT (INTERSECT all), duplicate rows are not eliminated.
Note: Several query result rows that use an operation word must be consistent.
12. Description: Use external connection
A, LEFT outer join:
Left OUTER join (left JOIN): The result set includes a matching row for the join table and all rows of the left join table.
Sql:select a.a, A.B, A.C, B.C, B.D, B.f from a left off JOIN b on a.a = B.C
b:right outer join:
Right outer join (right Join): The result set includes both the matching join row for the join table and all rows of the right join table.
c:full outer join:
Full outer joins: Includes not only the matching rows of the symbolic join table, but also all the records in the two join tables.
Next, let's look at some nice SQL statements

1. Description: Copy table (copy structure only, source table name: A new table name: B) (Access available)
Law one: SELECT * into B from a where 1<>1
Law II: SELECT top 0 * into B from a
2. Description: Copy table (copy data, source table name: A target table name: B) (Access available)
Insert into B (A, B, c) select d,e,f from B;
3. Description: Copy of table across databases (use absolute path for specific data) (Access available)
Insert into B (A, B, c) Select d,e,f from B in ' specific database ' where condition
Example:.. From B in ' "&server.mappath (". ") & "\data.mdb" & "' Where."
4, Description: Sub-query (table name 1:a table name 2:b)
Select A,b,c from a where a in (select D from B) or: Select A,b,c from a where a in (all-in-a-
5, Description: Display the article, the author and the last reply time
Select A.title,a.username,b.adddate from Table A, (select Max (adddate) adddate from table where Table.title=a.title) b
6, Description: External connection query (table name 1:a table name 2:b)
Select A.a, A.B, A.C, B.C, B.D, B.f from a left off JOIN b on a.a = B.C
7, Description: Online view query (table name 1:a)
SELECT * FROM (select A,b,c from a) T where t.a > 1;
8, Description: Between usage, between limits the query data range includes the boundary value, not between does not include
SELECT * FROM table1 where time between time1 and time2
Select A,b,c, from table1 where a is not between value 1 and value 2
9. Description: How to use
SELECT * FROM table1 where a [not] in (' Value 1 ', ' Value 2 ', ' Value 4 ', ' Value 6 ')
10, Description: Two related tables, delete the main table is already in the secondary table does not have information
Delete from table1 where NOT EXISTS (SELECT * from table2 where table1.field1=table2.field1)
11, Description: Four table linked to check the problem:
SELECT * from a left inner join B in a.a=b.b right inner join C on A.A=C.C inner join D on A.A=D.D where ...
12, Description: Schedule five minutes before the reminder
Sql:select * from schedule where DateDiff (' minute ', F start time, GETDATE ()) >5
13, Description: A SQL statement to take care of database paging
Select Top b.* from (select Top 20 primary key field, sort field from table name order by sort field desc) A, table name B where B. primary key field = A. primary key field order by a. Sort field
14, Description: The first 10 records
Select Top Ten * form table1 where range
15, Description: Select in each group B value the same data corresponding to a maximum record of all information (similar to the usage can be used in the forum monthly leaderboard, monthly hot product analysis, ranked by the subject score, and so on.)
Select A,b,c from tablename ta where a= (select Max (a) from TableName TB where tb.b=ta.b)
16. Description: Include all rows in TableA but not in TableB and TableC and eliminate all duplicate rows to derive a result table
(select a from TableA) except (select a from TableB) except (select a from TableC)
17, Description: Randomly remove 10 data
Select Top * FROM tablename ORDER by NEWID ()
18, Description: Random selection of records
Select NEWID ()
19. Description: Delete duplicate records
Delete from TableName where ID not in (the Select Max (ID) from tablename GROUP by Col1,col2,...)
20, Description: List all the table names in the database
Select name from sysobjects where type= ' U '

Summary of Classic and practical SQL Server statements (i)